I. Field
The present disclosure relates generally to communication, and more specifically to techniques for detecting adjacent channel interference (ACI) in wireless communication.
II. Background
Wireless communication systems are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These systems may be multiple-access systems capable of supporting multiple users by sharing the available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal FDMA (OFDMA) systems, and Single-Carrier FDMA (SC-FDMA) systems.
A system typically operates in accordance with a particular symbol rate and a particular carrier spacing between radio frequency (RF) channels. The symbol rate determines the bandwidth of a modulated signal transmitted on an RF channel. The carrier spacing determines the distance between adjacent RF channels. The system typically specifies a transmit mask for the modulated signal. The transmit mask defines the maximum and minimum amplitude values for the modulated signal over a range of frequencies. The transmit mask typically limits the bandwidth of the modulated signal on each RF channel to half of the symbol rate or less. However, the transmit mask specification may not be stringent, and a portion of the modulated signal on each RF channel may “bleeds” onto adjacent RF channels. For a given RF channel, the signal bleeding from an adjacent RF channel is referred to as adjacent channel interference (ACI).
ACI is one of several components that make up the total noise and interference observed by a receiver. ACI may degrade the received signal quality of a modulated signal, which may then adversely impact performance. Various techniques may be used to mitigate the deleterious effects of ACI. These techniques may improve performance when ACI is present but may actually degrade performance when ACI is not present. Hence, accurate detection of ACI is highly desirable in order to activate the ACI mitigation techniques only when applicable.